From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC409C4332F for ; Mon, 30 Oct 2023 11:22:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232294AbjJ3LWS (ORCPT ); Mon, 30 Oct 2023 07:22:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49696 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232938AbjJ3LWR (ORCPT ); Mon, 30 Oct 2023 07:22:17 -0400 Received: from mail-lf1-x133.google.com (mail-lf1-x133.google.com [IPv6:2a00:1450:4864:20::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF144B7 for ; Mon, 30 Oct 2023 04:22:14 -0700 (PDT) Received: by mail-lf1-x133.google.com with SMTP id 2adb3069b0e04-507c1936fd5so6106442e87.1 for ; Mon, 30 Oct 2023 04:22:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=semihalf.com; s=google; t=1698664933; x=1699269733; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=FprxzbI6BVQNgDI0NYQAcKjG+fc5xore7a8+UBbKX4c=; b=paVEpazkOFENpUS7tn27NMHDAAwG1Fp5RwgSC93HvcwGuCVk24mkXyv8rfW3tmveOB dEUhkYPtw4EGowHlabwh5YZwleeak4XDjNn+YRgj5efqQ3xoRUC+24Skwa2YwIbnHspT eQyQjAhuLvBlkXwVhlXXl3Aef81pzfBGqJpHcRj4z/GwTE2xfQ8C9yTgW32trB/bmUZR dLRltwamggqQA08n450aFWNx9JwQ/aIk0s0oDS4+ggLq8if9HmNXqMfxAIcdeTejTtyh pbFOxuxUo0U6wtbml/K5TmRAhXa5AmnRpfnIFi+3pJkN49m0QCiz1bM3amdkLUc6Twnh 4Zqw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698664933; x=1699269733; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=FprxzbI6BVQNgDI0NYQAcKjG+fc5xore7a8+UBbKX4c=; b=hxbnMkaTRCidFBXNNhZ/ONKHjLL3XSSMhpkAmnU08cw0pOaDitotPCW2h6qqL+bW8t thC29hLKcDknWOQYdVthUOpM5zP7tv03jTOS2c5J94S3ANUUJJgsvaKAvgybYpr1VEU2 guEGm414MLt9MamIdtjvacEo6H/pkGCl7ZB91HJDrl2kRgoulKx03BJF3Crzue1y7eh0 A8zw7x3fBX2rVFz7HMwFIyTc3TSkbZ+D0/RGOxxhRCXrTqG0uivjISbnSNzb8dB/FLUn lD4ZP2CGMYEb/OzZ+xd/o06Bp+Ja2++ogfuak0w44D4xfzEih1vuBze0JLKFbQBLqarT zqoA== X-Gm-Message-State: AOJu0YxCmiULMticY65RSIeamKwe+G1N9BmR2zHoTnsoHLuTgnmttW2B 8kFD9yHTNZzN5hzjaUca4x3QZw5kwUcUjcepSAE= X-Google-Smtp-Source: AGHT+IEz7reEqWFOUI5rj33H7xXhv/c1K1V8OKbIfrsL1y0CcBB/oJZdOqxtm8XZWnbNaYma0J5AIQ== X-Received: by 2002:a05:6512:2247:b0:504:33ff:156a with SMTP id i7-20020a056512224700b0050433ff156amr4292147lfu.11.1698664932369; Mon, 30 Oct 2023 04:22:12 -0700 (PDT) Received: from lmajczak1-l.roam.corp.google.com ([83.142.187.84]) by smtp.gmail.com with ESMTPSA id l11-20020a19c20b000000b00507ae0a5ea8sm1420559lfc.16.2023.10.30.04.22.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Oct 2023 04:22:11 -0700 (PDT) From: Lukasz Majczak To: stable@vger.kernel.org Cc: Lukasz Majczak , Radoslaw Biernacki , Manasi Navare Subject: [PATCH 4.14.y] drm/dp_mst: Fix NULL deref in get_mst_branch_device_by_guid_helper() Date: Mon, 30 Oct 2023 12:21:29 +0100 Message-ID: <20231030112129.137767-1-lma@semihalf.com> X-Mailer: git-send-email 2.42.0.820.g83a721a137-goog In-Reply-To: <2023102726-arousal-ransack-d969@gregkh> References: <2023102726-arousal-ransack-d969@gregkh> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org As drm_dp_get_mst_branch_device_by_guid() is called from drm_dp_get_mst_branch_device_by_guid(), mstb parameter has to be checked, otherwise NULL dereference may occur in the call to the memcpy() and cause following: [12579.365869] BUG: kernel NULL pointer dereference, address: 0000000000000049 [12579.365878] #PF: supervisor read access in kernel mode [12579.365880] #PF: error_code(0x0000) - not-present page [12579.365882] PGD 0 P4D 0 [12579.365887] Oops: 0000 [#1] PREEMPT SMP NOPTI ... [12579.365895] Workqueue: events_long drm_dp_mst_up_req_work [12579.365899] RIP: 0010:memcmp+0xb/0x29 [12579.365921] Call Trace: [12579.365927] get_mst_branch_device_by_guid_helper+0x22/0x64 [12579.365930] drm_dp_mst_up_req_work+0x137/0x416 [12579.365933] process_one_work+0x1d0/0x419 [12579.365935] worker_thread+0x11a/0x289 [12579.365938] kthread+0x13e/0x14f [12579.365941] ? process_one_work+0x419/0x419 [12579.365943] ? kthread_blkcg+0x31/0x31 [12579.365946] ret_from_fork+0x1f/0x30 As get_mst_branch_device_by_guid_helper() is recursive, moving condition to the first line allow to remove a similar one for step over of NULL elements inside a loop. Fixes: 5e93b8208d3c ("drm/dp/mst: move GUID storage from mgr, port to only mst branch") Cc: # 4.14+ Signed-off-by: Lukasz Majczak Reviewed-by: Radoslaw Biernacki Signed-off-by: Manasi Navare Link: https://patchwork.freedesktop.org/patch/msgid/20230922063410.23626-1-lma@semihalf.com (cherry picked from commit 3d887d512494d678b17c57b835c32f4e48d34f26) Signed-off-by: Lukasz Majczak --- drivers/gpu/drm/drm_dp_mst_topology.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 64faa70a9dd9..879638e6bea4 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -1268,14 +1268,14 @@ static struct drm_dp_mst_branch *get_mst_branch_device_by_guid_helper( struct drm_dp_mst_branch *found_mstb; struct drm_dp_mst_port *port; + if (!mstb) + return NULL; + if (memcmp(mstb->guid, guid, 16) == 0) return mstb; list_for_each_entry(port, &mstb->ports, next) { - if (!port->mstb) - continue; - found_mstb = get_mst_branch_device_by_guid_helper(port->mstb, guid); if (found_mstb) -- 2.42.0.820.g83a721a137-goog